Process for the manufacture of alkaline earth salts of inorganic acid esters and the like



i atented Oct. 10, 1939 UNITED STATES PATENT OFFICE Anton Johan Tulleners, Amsterdam, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application May 16, 1938, Serial No. 208,203. In the Netherlands May 31, 1937 11 Claims.

This invention relates to the production of organic salts which may be considered as derived from acid esters of polybasic mineral acids and metals which form insoluble salts with the corresponding free mineral acid. It is particularly concerned with the production of calcium, strontium, barium, lead and like salts of sulfuric and phosphoric esters having seven or more carbon atoms in the molecule. The invention provides an improved method whereby such salts may be obtained directly andeconomically from reaction products of sulfuric acid or other suitable sulfating agents, or the like with olefines, alcohols and similar esterifiable organic compounds of at least seven carbon atoms per molecule.

For the purpose of making my invention more clear it will be described with more particular reference to the manufacture of alkaline earth and lead salts of the higher alkyl sulfuric acid esters but it will be understood that this is merely in the interest of conciseness and implies no limitations as the process of the invention is applicable to the preparation of other ester salts which involve similar solubility relationships among the reactants.

I have found that in preparing sulfuric acid alkyl ester salts of metals which form Waterinsoluble sulfates, such as calcium, strontium, barium or lead sulfates, for example from reaction products, containing free sulfuric acid, of olefines or alcohols and sulfuric acid, difiiculties arise which are not encountered during manufacture of the more common alkali salts of similar sulfates. The water-insoluble sulfates of calcium, lead and the like which are produced on treatment of alkyl acid sulfates of seven or more carbon atoms containing free sulfuric acid are extremely difiicult to separate from the desired product. They are not only very difficult to filter because, as a rule they are of a colloidal nature but also they havethe property of so intensively adsorbing a considerable percentage of the alkyl ester salts being produced that these salts cannot be removed from the precipitates by washing. As a result the yield of pure product is low and its cost correspondingly high. The problem was recognized in U. S. Patent 1,998,411 Where it is recommended that the alkyl ester salts be formed by reaction with solid calcium oxide or the like under anhydrous conditions. Such a procedure involves a tedious masceratio-n of the lime which is both expensive and difficult to make effective, and results usually in incomplete reaction so that there is little net improvement over simple neutralization with an aqueous base.

In contradistinction .to the prior art methods, by the process of my invention a readily filterable precipitate is obtained, which can be freed almost entirely from any alkyl ester salts absorbed thereon by a simple Washing treatment. The process of my invention essentially comprises reacting free acid-containing acid esters of the previously defined type, with alkaline earth, lead or the like neutralizing agents in the presence of a ketone and/or an alcohol having not more than four carbon atoms in the molecule. The insoluble metal sulfates thus precipitated in an alcohol or ketone medium are of a crystalline nature and occlude almost no alkyl ester salts. My improved method of operation not only thus facilitates removal of the insoluble inorganic salt impurities from the product but also the progress of the neutralization was found to be favorably affected by the presence of alcohol or ketone.

Suitable ketones which may be used in the out in many different ways and the proportion of Q ketone and/ or alcohol used may be widely varied to meet different conditions. In general, good results may be obtained inthe case of olefine absorption products, for example, by adding a quantity of ketone and/or alcohol approximately ods of operation it may, however, be advanta-' geous to add the ketone or alcohol simultaneously with the metal compound used, a continuous stream of a sulfation product being, for

example mixed with a continuous stream of alcoholic milk of lime. It is essential that the precipitation be effected in the presence of the ketone and/oralcohol as the advantages attained by my procedure cannot be realized if the ketone or alcohol addition takes place only after the treatment with the chosen calcium or like compound.

A Wide range of temperatures may be used in the process of my invention. I prefer to employ elevated temperatures, however, as in this manner not only may the acid alkyl esters be converted into the desired calcium, strontium, barium or lead salts but also any neutral alkyl esters present may be saponified in the same operation. Temperatures up to the decomposition temperature of the desired salt may be employed using, if desired, elevated pressures. In general temperatures between about 60 to 120 C. are satisfactory for the production of alkaline earth salts of acid alkyl sulfates. The reactants may be mixed at normal temperature or at low temperatures controlled by suitable refrigerants and subsequently heated to effect saponification of the dialkyl sulfates, or the like to the desired alkyl sulfate salt and corresponding alcohol. The time of heating required in any particular case will depend upon the amount and nature of the alkyl esters involved. Three or four hours boiling under reflux at atmospheric pressure is usually sufficient where alkaline earth salts of secondary alkyl sulfates derived from olefines of about 10 to 20 carbon atoms per molecule are being prepared. By the use of higher temperatures and superatmospheric pressures the heating time may be greatly reduced. In the absence of polyalkyl esters the heating may be further reduced.

It is advantageous to remove a part of the free sulfuric acid before applying the process of my invention. This may, for example, be effected by washing with controlled amounts of water or an aqueous medium as described in my Patent No. 2,078,516.

After the conversion to calcium, strontium, barium or lead salts, the reaction mixture may be extracted With suitable immiscible solvents, advantageously hydrocarbons, such as pentane, benzene or gasoline, or the like, to remove the hydrocarbon soluble impurities such for example, as polymers, etc. Such impurities, unless removed, tend to deposit on the filter cake of insoluble metal sulfates making it less permeable. Other method of purifying the product either before or after removal of the insoluble sulfate precipitate may be used.

The following examples illustrating typical applications of the process of my invention. as applied to the manufacture of calcium alkyl sulfates of thirteen to eighteen carbon atoms, show in somewhat more detail how the process may be applied and make clear the efficiency of the method.

Example I 100 parts by weight of a cracking distillate boiling between 220 and 310 C. (with a bromine figure McIlhiney=56.5) containing alkenes with 13 to 18 carbon atoms inclusive and obtain-ed by cracking paraffin wax in the vapor phase, were treated for one hour at 0-5 C. with double the molar quantity of 90% sulfuric acid (calculated on the bromine figure).

By the addition of 14 parts by Weight Water, by far the greater part (about 90%) of the nonbound acid was separated off from the reaction product obtained as a waste acid of about 70% concentration.

The substantially de-acidified product thus obtained was worked up to calcium alkyl sulfate by heating it to about 80 C. with 47 parts by weight of milk of lime of about 33.5% concentration, after the addition of 240 parts by weight ethanol of 50% concentration.

The calcium sulfate, excess calcium hydroxide, etc. were then removed by filtering the saponification product, after this had been previously mixed with 150 parts by weight of a benzine boiling between 80 and 130 C. The filter cake thus obtained amounted to parts by weight and contained, besides calcium sulfate, calcium hydroxide and water, 2.6 parts by weight calcium alkyl sulfate and 9 parts by weight polymerization products. If no benzine was added before the filtration, a filter cake was produced which contained 5.5 parts by weight calcium alkyl sulfate and 25.6 parts by weight polymerization products.

By washing the filter cake with hot ethanol of 50% concentration the calcium alkyl sulfate could be completely recovered, whilst by evaporation of the combined filtrates, after removal of the polymerization products by extraction with benzine, a paste-like mass was obtained consisting almost exclusively of calcium alkyl sulfate and water, and containing 63 parts by weight calcium alkyl sulfate.

Example II 100 parts by weight of a cracking distillate boiling between 220 and 310 C. (with a bromine figure Mcllhiney=58.4), containing alkenes with 13 to 18 carbon atoms inclusive and obtained by cracking parafiin wax in the vapor phase, were treated for one hour at 05 C. with double the molar quantity of 90% sulfuric acid (calculated on the bromine figure).

By the addition of 14 parts by weight water by far the greater part (about 90%) of the nonbound acid was separated from the reaction product obtained, as a waste acid of about 70% concentration.

The substantially de-acidified product thus obtained was then worked up to calcium alkyl sulfate by heating it with 58 parts by weight milk of lime of about 33.5% concentration, after the addition of 125 parts by weight acetone and 100 parts by weight water. The mixture was heated, whilst stirring, for about 6 hours at a temperature of 6065 C. and the neutralization product was then filtered in order to remove calcium sulfate, calcium hydroxide, etc. The filter cake obtained as a result of this filtration, which proceeded very smoothly, amounted to 62 parts by weight and contained, besides calcium sulfate, calcium hydroxide and water, 3.3 parts by weight calcium alkyl sulfate and 21.0 parts by weight polymerization products.

The calcium alkyl sulfate could be almost completely recovered from the filter cake by washing, whilst by evaporation of the combined acetonecontaining filtrates, after removal of the polymerization products by extraction (just as in the case of ethanol being used instead of acetone), a paste-like mass, consisting almost exclusively of calcium alkyl sulfate and water, was obtained, which mass contained 64 parts by weight calcium alkyl sulfate.

The acetone could be recovered by distillation.

It will be apparent that the process of my invention offers many advantages, particularly in efficiency and completeness of separation of insoluble inorganic salts and alkyl ester salts and consequently in freedom from losses. The completeness of the removal of calcium, strontium, barium and lead sulfates which may be achieved by effecting their precipitation in the presence of a ketone and/or alcohol of not more than four carbon atoms not only leads to higher yields of the corresponding alkyl ester salts but also a greatly superior product of much improved purity. The calcium alkyl sulfates obtained from olefines of '7 to 9 and of 10 to 12 carbon atoms per moleculeby the process of my invention had much better foaming properties, for example, than the corresponding sodium salts. Calcium, strontium, barium and lead salts of alkyl sulfate in the pure form obtainable by the process of myinvention have the further advantage of being more soluble in water than are similar products contaminated with inorganic salts, particularly sodium salts. Due to their purity my products have a much wider field of usefulness than is the case with impure salts.

Although the process of my invention is more particularly of importance in the preparation of calcium, strontium, barium and/or lead salts of acid sulfuric esters of olefines or alcohols, it may also be applied to the preparation of salts of these metals derived from sulfuric or phosphoric acide esters of other organic compounds such as unsaturated alcohols, mixed aliphatic-cyclic hydrocarbons having one or more olefinic bonds, etc. My invention is thus not only capable of wide variations with respect to the organic esters which may be used as starting material and the reaction conditions employed but also the operating details may be greatly varied. For example, it will be evident that centrifugation and/or decantation may be used for separating the insoluble inorganic salts precipitated in accordance with my invention, instead of the filtration methods described in the foregoing examples. Furthermore, it will be clear that instead of adding the water insoluble polymer solvent after the precipitation step, it may be introduced simultaneously with the ketone or alcohol employed. It will therefore be evident that my invention is not to be limited to the details described nor by any theory advanced in explanation of the advantageous results attained, but only by the terms of the accompanying claims in which it is my intention to claim all novelty inherent therein as broadly as possible in view of the prior art.

I claim as my invention:

1. A process for producing alkaline earth salts ofalkyl sulfates which comprises treating, at a temperature between 60 and 120 C., a sulfuric acid-containing alkyl acid sulfate of at least seven carbon atoms with a basic alkaline earth metal compound in the presence of sufficient acetone to cause precipitation of crystalline alkaline earth metal sulfate.

2. A process for producing pure calcium alkyl sulfates which comprises treating a sulfuric acid absorption product of an olefine of at least seven carbon atoms per molecule with calcium hydroxide in the presence of sufiicient of an aliphatic ketone having not more than four carbon atoms per molecule to cause precipitation of crystalline calcium sulfate at a temperature between. about 60 and 120 (3., adding a liquid hydrocarbon to the reaction product and filtering off the precipit'ated calcium sulfate.

3. A process for producing lead salts of acid alkyl esters of polybasic mineral acids which form water-insoluble lead salts which comprises reacting at a temperature between about 60 and 120 0., a mixture containing an acid alkyl ester of at least seven carbon atoms per molecule and said acid in the free state with a basic lead compound in the presence of sufficient of a member of the class consisting of aliphatic ketones and alcohols having not more than four carbon atoms in the molecule to cause precipitation of a crystalline lead salt of said acid.

4. A process for producing alkaline earth metal salts of acid alkyl sulfates of at least seven carbon atoms per molecule which comprises reacting, at an elevated temperature below the decomposition temperature of said alkyl sulfate salt, an absorption product of an olefine of at least seven carbon atoms per molecule in sulfuric acid with a basic alkaline earth metal compound in the presence of sufficient of a member of the class consisting of aliphatic ketones and alcohols having not more than four carbon atoms in the molecule to cause precipitation of a crystalline alkaline earth metal sulfate.

5. A process for producing lead alkyl sulfates which comprises reacting a mixture of an acid alkyl sulfate of at least seven carbon atoms per molecule and free sulfuric acid with a basic lead compound in the presence of suflicient of an aliphatic ketone having not more than four carbon atoms in the molecule to cause precipitation of a crystalline lead sulfate.

6. A process for producing calcium alkyl sulfates which comprises reacting a mixture of an acid alkyl sulfate of at least seven carbon atoms per molecule and free sulfuric acid with lime in the presence of sufficient of an aliphatic ketone having not more than four carbon atoms in the molecule to cause precipitation of crystalline calcium sulfate.

7 A process for producing alkaline earth metal salts of acid alkyl sulfates of at least seven carbon atoms per molecule which comprises reacting a mixture of said acid alkyl sulfate and free sulfuric acid with a basic alkaline earth metal compound in the presence of sufficient of an aliphatic ketone having not more than four carbon atoms in the molecule to cause precipitation of a crystalline alkaline earth metal salt of said acid.

8. A process for producing alkaline earth salts of acid alkyl esters having at least seven carbon atoms per molecule which are derived from polybasic mineral acids which form water-insoluble inorganic alkaline earth metal salts which comprises reacting a mixture containing said acid ester and the free polybasic mineral acid corresponding thereto with a basic alkaline earth metal compound in the presence of sufiicient of a member of the group consisting of ketones and alcohols of not more than four carbon atoms per molecule to cause precipitation of a crystalline alkaline earth metal salt of said acid.

9. A process for producing salts of acid alkyl phosphates of at least seven carbon atoms per molecule and metals which form water-insoluble inorganic phosphates which comprises reacting a mixture of an acid alkyl phosphate and free phosphoric acid with a basic acting compound of said metal in the presence of sufficient of a member of the group consisting of ketones and alcohols .of not more than four carbon atoms per molecule to cause precipitation of a crystallinephosphate of said metal.

10. A process for producing salts of acid alkyl sulfates of at least seven carbon atoms per molecule and metals which form water-insoluble inorganic sulfates which comprises reacting a mixture of an acid alkyl sulfate and free sulfuric acid with a basic acting compound of said metal in the presence of suflicient of a member of the group consisting of ketones and alcohols of not more than four carbon atoms per molecule to cause precipitation of a crystalline sulfate of said metal.

11. A process for producing salts of acid esters of polybasic mineral acids having at least seven of sufiicient of a member of the group consisting of ketones and alcohols of not more than four carbon atoms per molecule to cause precipitation of a crystalline salt of said inorganic acid and said metal.

ANTON JOHAN TULLENERS. 

